Nonequilibrium quantum phenomena are a rapidly developing field of research, both experiment and theory. They arise in very different areas of physics, ranging from electronic quantum materials and magnetism to cosmology, with similar concepts arising in their theoretical description. The parallels between cosmology and condensed matter physics with Landau’s concept of a symmetry breaking transition have led to the Standard model, Higgs mass (from superconductivity) and inflation theories (from first-order transitions). The condensed matter playground is much more experimentally tractable, allowing easier validation of new physical concepts on one hand, and discovery of new phenomena on the other. This leads to the idea of real-time investigations of elementary collective excitation dynamics through phase transitions with femtosecond optical experiments in quantum matter.
The focus of the proposed research is the study of detailed temporal evolution of quantum materials emerging from a phase transition on extended timescales. The systems of interest all evolve in time, undergoing symmetry breaking transitions. The time-scales on which events occur are very wide: while electronic structure responds in femtoseconds, domains rearrange on timescales ranging from femtoseconds to centuries and their quantum dynamics represent a vast unexplored area of quantum physics.
In the last decade, the investigation of phase transitions in real time has become very intense, particularly with the development of new optical pump-probe spectroscopy methods and numerous synchrotron and free electron laser facilities which allow probing of nonequilibrium phenomena by everything from X-rays and light down to THz frequencies. The roles of single particle and collective excitations (phonons, magnons etc.) in phase transitions has been investigated in detail on the femtosecond timescale in a wide variety of materials, including charge-ordered and magnetic materials, superconductors, in 1D, quasi-2D materials, single monolayer stacks, as well as in structural transitions. Research in this kind of physics requires identification of appropriate model systems that can be used to reveal new phenomena. All-optical ultrafast time-resolved spectroscopy offers, due to its relative simplicity, a perfect tool for exploratory research of exotic phenomena in new materials.
The research will be therefore focused on exploratory research of ultrafast time resolved optical response in strongly excited novel electronically ordered materials focusing on (but not limited to) 2D charge and/or magnetically ordered systems in bulk as well as thin flake form. Heterostructures formed from such materials will also be studied.